A radio frequency, RF, switch, e.g., for a wireless antenna, may comprise a plurality of switches coupled in series. An RF peak voltage (which may reach 80 V in some cases) can lead to the creation of an unwanted conductive path between the terminals of the switches and other elements, such as ground metal lines. In particular, the switches closer to the high-voltage terminal tend to experience a higher voltage drop than the switches at the low-voltage terminal. In general terms, the more the stacked switches and/or the larger the parasitic capacitance of each switch to the ground, the more the effect is pronounced. Therefore, among the switches, unequal voltage drops are caused.
Each switch (which may be a transistor, such as a metal-oxide-semiconductor field-effect transistor, MOSFET) has in general a low voltage-handling capability, and, therefore, different voltage drops at different switches are unwanted. In an attempt to equalize the voltage drops at the different switches of the series, a technique has been proposed, according to which capacitors are connected in parallel to the switches. Capacitors with high capacitance have been associated to switches closer to the high-voltage terminal, while capacitors with low capacitance have been associated to switches closer to the low-voltage terminal.
This technique defines a unique direction in the series and is only advantageous for the applications in which it is determined a priori which of the terminals will be the high-voltage terminal of the series. In applications for which, for example, the series is operated at the opposite voltage, the capacitors will have the unwanted effect of increasing the inequalities between the voltage drops.